Neodymium doped lanthanum oxysulfide as optical temperature sensors

The fluorescence intensity ratio (FIR) technique for temperature sensing has been demonstrated in La2O2S:Nd3+ phosphors. The phosphors were extensively characterized using various methods such as X-ray diffraction, photoluminescence excitation, and photoluminescence spectra. Upon ultraviolet-visible (UV-vis) or near-infrared (NIR) light excitation, two intense NIR emissions of Nd3+ peaking at 897 nm and 1074 nm corresponding to transitions of F-4(3/2)-> I-4(9/2) and F-4(3/2)-> I-4(11/2) were generated at room temperature. NIR emission of Nd3+ in a wide temperature range from 30 K to 600 K was investigated. Experimental results show that the temperature evaluation can be realized by monitoring the emission peak position, measuring the fluorescence intensity ratio of F-4(5/2) and F-4(3/2) or that of the two Stark components of the F-4(3/2) level in the bulk La2O2S:Nd3+. Furthermore, the effective energy difference of the thermalized levels F-4(5/2) and F-4(3/2), and F-4(3/2) two Stark components were 987 cm(-1) and 110 cm(-1), respectively. Those results imply that La2O2S:Nd3+ phosphor is a potential candidate for the optical temperature sensor. (C) 2013 Elsevier B.V. All rights reserved.